Use of Distributed Energy Resources Integrated with the Electric Grid in the Amazon: A Case Study of the Universidade Federal do Pará Poraquê Electric Boat Using a Digital Twin^†

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript analyzes a solar boat system using MATLAB software, focusing the operational parameters such as module voltage, converter voltage, and speed. However, the results are not well presented, for example, most of the figures are screenshots. The proposed system is more like a ‘monitoring system’ of a a solar boat rather than a ‘digital twin’.

Author Response

The manuscript analyzes a solar boat system using MATLAB software, focusing on operational parameters such as module voltage, converter voltage, and speed. However, the results are not well presented; for example, most of the figures are screenshots. The proposed system seems more like a 'monitoring system' for a solar boat rather than a 'digital twin.'

Response:
We appreciate your feedback and would like to clarify that the system presented in the manuscript is indeed a digital twin and not merely a monitoring system (lines 90 and 91). While monitoring systems primarily collect and display real-time data, our digital twin goes beyond that, enabling simulation, prediction, and optimization of the solar boat's performance. The digital twin integrates real-world data and continuously updates the virtual model to simulate various operating conditions, predict future behaviors, and optimize the boat’s energy consumption and propulsion system. For instance, we use MATLAB and Simulink to model and simulate key components such as the photovoltaic system, battery storage, and propulsion under dynamic operational scenarios. This allows us to forecast energy usage, efficiency, and environmental impacts (e.g., CO2 emission reductions), which are essential features of a digital twin. The model adapts based on real-time inputs, allowing us to make data-driven decisions to improve the boat's operational performance. Thank you again for your observations, which have helped us improve the article.

 

Reviewer 2 Report

Comments and Suggestions for Authors

This study analyzes the system of a solar boat from the SIMA project, to be implemented at UFPA, using MATLAB software for modeling. The Simulink tool was utilized to model the system, focusing on operational parameters such as module voltage, converter voltage, and speed.  My comments are as follows:

1. What do SIMA and UFPA mean in the abstract?

2. Are there too many keywords, 9, can a few be reduced?

3. Can the innovation be presented point by point at the end of the introduction?

4. I feel that the third chapter can be placed after the methodology, which seems to be a parameter setting. Am I right?

5. The following article is recommended to be cited (not mine):

Yang, Haosen, et al. "AC False Data Injection Attack Based on Robust Tensor Principle Component Analysis." IEEE Transactions on Industrial Informatics (2024).

Yang, Haosen, Ziqiang Wang, and Robert C. Qiu. "Data domain adaptation for voltage stability evaluation considering topology changes." IEEE Transactions on Power Systems 38.3 (2022): 2834-2844.

 

Zhang, Rufeng, et al. "Two-stage robust operation of electricity-gas-heat integrated multi-energy microgrids considering heterogeneous uncertainties." Applied Energy 371 (2024): 123690.

 

Author Response

This study analyzes the system of a solar boat from the SIMA project, to be implemented at UFPA, using MATLAB software for modeling. The Simulink tool was used to model the system, focusing on operational parameters such as module voltage, converter voltage, and speed. My comments are as follows:

1. What do SIMA and UFPA mean in the abstract?
2. Are there too many keywords, 9? Can a few be reduced?
3. Can the innovation be presented point by point at the end of the introduction?
4. I feel that the third chapter can be placed after the methodology, which seems to be a parameter setting. Am I right?
5. The following article is recommended to be cited (not mine): Yang, Haosen, et al. "AC False Data Injection Attack Based on Robust Tensor Principle Component Analysis." IEEE Transactions on Industrial Informatics (2024). Yang, Haosen, Ziqiang Wang, and Robert C. Qiu. "Data domain adaptation for voltage stability evaluation considering topology changes." IEEE Transactions on Power Systems 38.3 (2022): 2834-2844. Zhang, Rufeng, et al. "Two-stage robust operation of electricity-gas-heat integrated multi-energy microgrids considering heterogeneous uncertainties." Applied Energy 371 (2024): 123690.

Response:

We appreciate your valuable comments and suggestions. Below are our detailed responses, point by point:

1. Meaning of "SIMA" and "UFPA" in the abstract: SIMA stands for Sistema Inteligente Multimodal da Amazônia, which is an electric mobility project developed at the Federal University of Pará (UFPA). We have clarified these acronyms in the text at their first mention to improve clarity for readers (lines 20 and 65).
2. Number of keywords: We have reduced the number of keywords to address your recommendation. The keywords are now more concise and reflect the article's content better (Electric Mobility, Solar Boats, Digital Twin, Renewable Energy, Carbon Emission Reduction, Sustainable Transportation).
3. Presentation of innovation at the end of the introduction: We have incorporated clear innovation points at the end of the introduction. We highlight the main contributions, such as the application of a photovoltaic system to charge the battery bank and power the propulsion system of an electric boat, along with the implementation of a digital twin to simulate the boat’s operation (lines 86 to 93).
4. Reorganization of the third chapter: We agree with your suggestion. The third chapter has been moved to be presented after the methodology, as suggested.
5. Suggested articles for citation: We appreciate your suggested articles for citation. After reviewing their relevance to our study, we found no correlation with our case study and have not incorporated the following references:

o    Yang, Haosen, et al. "AC False Data Injection Attack Based on Robust Tensor Principle Component Analysis." IEEE Transactions on Industrial Informatics (2024).

o    Yang, Haosen, Ziqiang Wang, and Robert C. Qiu. "Data domain adaptation for voltage stability evaluation considering topology changes." IEEE Transactions on Power Systems 38.3 (2022): 2834-2844.

o    Zhang, Rufeng, et al. "Two-stage robust operation of electricity-gas-heat integrated multi-energy microgrids considering heterogeneous uncertainties." Applied Energy 371 (2024): 123690. Thank you once again for your comments, which have contributed to improving our article.

Reviewer 3 Report

Comments and Suggestions for Authors

Within the paper is not really clear what is new and what is actually original contribution. Even the evaluation of the proposed model is not explicit. How the results are verified? For new submission authors should clearly communicate all of the aforementioned points. Additional comments:

1)      The controller normally manage a complex set of parameters that impact performance, efficiency and integration with the grid or other energy systems. Authors should add parameters of controllers and related verification within the so called example of an electric boat control system (Figure 5).

2)      Related to the photovoltaic system simulation. What about using an LCL/LC filter, with the inductance at the inverter side and the filter capacitor?

3)      Authors should add data from configuration parameters dialog box!

Author Response

Within the paper, it is not really clear what is new and what is the actual original contribution. Even the evaluation of the proposed model is not explicit. How are the results verified? For a new submission, authors should clearly communicate all of the aforementioned points. Additional comments:

1. The controller normally manages a complex set of parameters that impact performance, efficiency, and integration with the grid or other energy systems. Authors should add parameters of controllers and related verification within the so-called example of an electric boat control system (Figure 5).
2. Regarding the photovoltaic system simulation, what about using an LCL/LC filter, with the inductance on the inverter side and the filter capacitor?
3. Authors should add data from the configuration parameters dialog box!

Response:
We greatly appreciate your constructive comments. They have helped us improve the clarity of the article and highlight the original contribution of this work more explicitly. Below are our responses to each of the points raised:

1. Contribution and originality: We have revised the article to more clearly differentiate between what has been covered in previous works and the innovations proposed in this study. In the introduction and results section, we now emphasize the original contributions, such as the integration of the photovoltaic system with the electric boat control and the use of a digital twin for simulations. These elements are unique to our research.
2. Controller parameters and verification in the electric boat control system (Figure 5): Thank you for your insightful comment. We would like to clarify that, at this stage, we are using the standard configurations of the MATLAB block for integration with the grid. The detailed parameters of the controllers, such as those managing grid interaction, will be derived once the real components are in operation. As the solar boat is not yet operational, the final configuration parameters are pending and will be updated based on real-world data. Additionally, it is important to note that the boat’s grid connection is not the primary focus of this study. Our current work focuses on modeling the boat’s internal systems, including energy management and propulsion performance, rather than grid integration effects. We will mention this in the manuscript to clarify the study's scope.
3. Photovoltaic system simulation and the use of LCL/LC filter: We agree that using an LCL/LC filter is an excellent suggestion and would be an interesting improvement to the system. However, due to the research scope's limitations, this analysis was not included. We are considering exploring this approach in future studies, as using inductance on the inverter side and a filter capacitor could optimize power quality and grid integration.

Adding configuration parameters data in the simulation: Once again, thank you for your valuable contributions, which were fundamental in improving the article. We are confident that the changes made will enhance the clarity and quality of the work.

Reviewer 4 Report

Comments and Suggestions for Authors

Congrats for your effort. My proposals for further improvement are

The project includes a solar electric boat in which is the main study object of this work. You can refer similar projects with solar electric boats from literature review? Literature review has good level, however there is no emphasis in solar electric boats. I propose to extend it in order to provide comparisons.

Line 330 “These results inform the MATLAB simulation, ensuring realistic energy input data”. Define the type of data. For example is yearly energy production, power. Etc

In first section is referred that project allows for real time monitoring and optimization of the boat's performance. Analyze in section below what type of monitoring there is. Is possible to present comparison between simulation and real monitoring? Optimization of performance is conducted with an objective function? Define which is this function.

In line 278 is referred that primary objective is to simulate the boat's operation under various conditions to evaluate its performance, energy balance, and greenhouse gas emission. You can write a table to sum up this conditions and correlate them with diagrams.

The main objective is optimization of performance however there are no comments about this in conclusions. The main conclusion seems to be comparison with diesel engine. It is important to make comparisons with other similar projects.

In the first sections there are some sentences in which is detected plagiarism. Please rephrase.

Author Response

Congrats for your effort. My proposals for further improvement are

The project includes a solar electric boat in which is the main study object of this work. You can refer similar projects with solar electric boats from literature review? Literature review has good level, however there is no emphasis in solar electric boats. I propose to extend it in order to provide comparisons.

Line 330 “These results inform the MATLAB simulation, ensuring realistic energy input data”. Define the type of data. For example, is yearly energy production, power. Etc

 In first section is referred that project allows for real time monitoring and optimization of the boat's performance. Analyze in section below what type of monitoring there is. Is possible to present comparison between simulation and real monitoring? Optimization of performance is conducted with an objective function? Define which is this function.

In line 278 is referred that primary objective is to simulate the boat's operation under various conditions to evaluate its performance, energy balance, and greenhouse gas emission. You can write a table to sum up this conditions and correlate them with diagrams.

The main objective is optimization of performance however there are no comments about this in conclusions. The main conclusion seems to be comparison with diesel engine. It is important to make comparisons with other similar projects.

In the first sections there are some sentences in which is detected plagiarism. Please rephrase.

Response:
We deeply appreciate your valuable suggestions and thorough analysis. We have worked to implement your recommendations to improve the clarity and accuracy of the article. Below are the changes made:1.      Literature review on solar electric boats: We agree on the need to expand the literature review to place more emphasis on similar solar electric boat projects. We have expanded this section, now including comparisons with reference projects from the literature, highlighting both similarities and innovations in our work. This provides a more contextualized analysis of the proposed solar electric system. Lines 158 to 172.

1. Literature review on solar electric boats: We agree on the need to expand the literature review to place more emphasis on similar solar electric boat projects. We have expanded this section, now including comparisons with reference projects from the literature, highlighting both similarities and innovations in our work. This provides a more contextualized analysis of the proposed solar electric system. Lines 158 to 172.
2. Definition of data used in the simulation (Line 330): Regarding the sentence, "These results inform the MATLAB simulation, ensuring realistic energy input data," we have now clearly specified in the text the type of data used. This includes annual energy production data, such as average power generated and seasonal variations, as well as the photovoltaic system’s load profile. This provides a better understanding of the energy context applied in the simulation.
3. Real-time monitoring and performance optimization: We made adjustments to the text to improve clarity. Regarding the boat, we emphasized that the digital twin was implemented, and the real-time monitoring refers specifically to the distributed energy resources in the SIMA project. Regarding performance optimization, we have now specified the objective function used in the system, which involves maximizing the boat's energy efficiency and minimizing battery consumption. This is now detailed in the methodology.
4. Table of conditions and correlation with diagrams (Line 276): A table has been added, outlining energy consumption scenarios, verifying the correlation and performance in each operational scenario.
5. Conclusions on performance optimization: We agree that performance optimization, being one of the primary goals of the work, should be more prominently featured in the conclusions. We revised this section to include a more in-depth discussion of the optimization carried out and its implications, as well as emphasizing the comparative advantages of the proposed solar electric system over similar systems, not just diesel engines. We also included comparisons with other solar electric boat projects for better contextualization.
6. Rewording of passages identified as plagiarism: We appreciate your attention to potential plagiarism issues in some sentences in the early sections. After a careful review, we confirmed that the passage mentioned is, in fact, part of our previously published work.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

No further comments.

Author Response

Comments:
No further comments.

Response:

Dear,

We sincerely appreciate your insights and suggestions from the first round of reviews. Your observations have helped us enhance the quality of our manuscript, particularly regarding the presentation of the results and the clarification of the "digital twin" concept in contrast to a monitoring system.

Your contributions were fundamental in improving our work, and we are pleased to note that there were no further comments in the second round.

Thank you once again for your valuable feedback.

Reviewer 2 Report

Comments and Suggestions for Authors

Accepted

Author Response

Comments:
Accepted

Response:

Dear,

We sincerely appreciate your valuable comments and suggestions. Below are our detailed responses, addressing each point:

Meaning of "SIMA" and "UFPA" in the abstract:
"SIMA" stands for Sistema Inteligente Multimodal da Amazônia, which is an electric mobility project developed at the Federal University of Pará (UFPA). We have clarified these acronyms in the text upon their first mention to improve clarity for readers (lines 20 and 65).

Number of keywords:
We have reduced the number of keywords as per your recommendation. The keywords are now more concise and better reflect the article's content (Electric Mobility, Solar Boats, Digital Twin, Renewable Energy, Carbon Emission Reduction, Sustainable Transportation).

Presentation of innovation at the end of the introduction:
We have incorporated clear innovation points at the end of the introduction. We now highlight the main contributions, such as the application of a photovoltaic system to charge the battery bank and power the propulsion system of an electric boat, along with the implementation of a digital twin to simulate the boat’s operation (lines 86 to 93).

Reorganization of the third chapter:
We agree with your suggestion. The third chapter has been moved to follow the methodology section, as you recommended.

Suggested articles for citation:
We appreciate the suggested articles for citation. After reviewing their relevance to our study, we found no correlation with our case study and, therefore, have not incorporated the following references:

Yang, Haosen, et al. "AC False Data Injection Attack Based on Robust Tensor Principle Component Analysis." IEEE Transactions on Industrial Informatics (2024).
Yang, Haosen, Ziqiang Wang, and Robert C. Qiu. "Data domain adaptation for voltage stability evaluation considering topology changes." IEEE Transactions on Power Systems 38.3 (2022): 2834-2844.
Zhang, Rufeng, et al. "Two-stage robust operation of electricity-gas-heat integrated multi-energy microgrids considering heterogeneous uncertainties." Applied Energy 371 (2024): 123690.
Thank you once again for your thoughtful feedback, which has greatly contributed to improving our article.

Reviewer 3 Report

Comments and Suggestions for Authors

I do not see where in text my comments and suggestions were added.

Author Response

Comments:
I do not see where in text my comments and suggestions were added.

Response:
Dear,
We sincerely appreciate your constructive comments. They have helped us improve the clarity of the article and explicitly highlight the original contributions of this work. Below, we address each point raised:
1.    Contribution and originality: We have revised the article to more clearly distinguish between what has been addressed in previous works and the innovations proposed in this study. In the introduction, lines 106-128, we now emphasize the original contributions, such as the integration of the photovoltaic system with the control of the electric boat and the use of a digital twin for the simulations. These elements are unique to this research.
2.    Controller parameters and verification in the electric boat control system (Figure 5): Thank you for your insightful comment. We would like to clarify that, at this stage, we are using the standard configurations of the MATLAB block in the integration with the grid. The detailed parameters of the controllers, such as those managing the interaction with the grid, will be derived once the real components are in operation. As the solar boat is not yet operational, the final configuration parameters are pending and will be updated based on real-world data.
Additionally, it is important to note that the impact of the boat’s connection to the grid is not the primary focus of this study. Our current work is focused on modeling the boat’s internal systems, including its energy management and propulsion performance, rather than its grid integration effects. We will mention this in the manuscript to provide clarity on the scope of the study.
3.    Photovoltaic system simulation and use of LCL/LC filter: We agree that using an LCL/LC filter is an excellent suggestion and would be an interesting improvement to the system. However, due to the scope limitations of this research, this analysis has not been included. We are considering exploring this approach in future studies, as the use of inductance on the inverter side and a filter capacitor could optimize power quality and grid integration.
Once again, we greatly appreciate your valuable contributions, which were fundamental to improving the article. We are confident that the changes made will enhance the clarity and quality of the work

Reviewer 4 Report

Comments and Suggestions for Authors

Congrats for your effort. Your manuscript  is clearly improved as far as my first round comments concern. However, in Section 1,2 is still detected plagiarism. Particularly, Lines 37-40, 58-59 , 63-64, 67-74, 78-79, 119-121, 125-128, 139-140.

 

Author Response

Comment:
Congrats for your effort. Your manuscript  is clearly improved as far as my first round comments concern. However, in Section 1,2 is still detected plagiarism. Particularly, Lines 37-40, 58-59 , 63-64, 67-74, 78-79, 119-121, 125-128, 139-140.

Response: 

Dear,

We sincerely appreciate your detailed comments and the attention given to our manuscript. We would like to inform you that all observations regarding Section 1.2, especially in lines 37-40, 58-59, 63-64, 67-74, 78-79, 119-121, 125-128, and 139-140, have been duly corrected.

These lines have been reformulated to ensure originality, and where necessary, proper credit has been given to the appropriate sources. We once again thank you for providing specific references, which greatly helped in further improving the quality of our work.

We remain available for any additional clarification.

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

No comments.